Metal working lubricant

ABSTRACT

THIS INVENTION RELATES TO A LUBRICANT FOR METAL WORKING, SUCH AS A FORGING, WHICH CONTAINS A MAJOR PORTION OF POLYBUTENE AND MINOR PORTIONS OF TIN OR LEAD SOAPS, A SOLID LUBRICANT, SUCH AS GRAPHITE, AND A DISPERSING AGENT. FOR HOT FORGING, IT IS PREFERRED TO DILUTE THE LUBRICANT WITH KEROSENE OR THE LIKE.

United States Patent 3,806,453 METAL WORKING LUBRICANT Ewell E. McDole,Danville, Calif., assignor to Kaiser Aluminum & Chemical Corporation,Oakland, Calif. No Drawing. Filed Feb. 23, 1973, Ser. No. 335,087 Int.Cl. Cm 3/34 US. Cl. 252-22 17 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to a lubricant for metal Working, such as a forging,which contains a major portion of polybutene and minor portions of tinor lead soaps, a solid lubricant, such as graphite, and a dispersingagent. For hot forging, it is preferred to dilute the lubricant withkerosene or the like.

BACK-GROU ND This invention relates to the forging of metal productsand, more specifically, is directed to a lubricant for the forging oflight metal products.

Conventional press forging operations usually comprise at least twoforging steps, namely, a blocking step which preforms the workpiece andprovides the desired grain orientation and a finishing step which, asthe name implies, provides the final desired finished shape. Thefinishing step may involve multiple forging strokes if the finishedshape is complex. Generally, lubricant is applied to the dies and/ orworkpiece before each forging stroke.

Heretofore, the forging lubricants were generally a mixture of graphiteand a light oil carrier. Frequently, the mixture contained a metal soapto aid or assist in the lubrication. Although the conventionallubricants provided adequate lubrication for forging, they werecharacterized by the copious evolution of smoke and fumes. The emissionsare a mixture primarily of thermal degradation products and unburnedhydrocarbons. When forging complicated parts, where the die face hasdeep channels or complicated cavities, a large excess of lubricant wasnormally applied to insure that lubricant covered the entire diesurface. However, this large excess of lubricant substantially increasedthe evolution of smoke and fumes which were already excessive. Attemptshave been made to reduce the level of emissions by employing a lowerviscosity oil carrier or to dilute the lubricant with kerosene or thelike, in order to fiash off and burn the carrier rather than allowingthe thermal degradation to occur with its resultant problem withemissions. However, this usually required employing a lower dietemperature which increases the power requirements for the forgingoperations, aggravates the problem of the workpiece sticking to the die,and significantly reduces die life, particularly when complex diesurfaces are involved.

Against this background, the present invention was developed.

DESCRIPTION OF THE INVENTION The lubricant of the present inventioncomprises a carrier fluid of polybutene, a solid lubricant, a tin orlead soap and a dispersing agent. Other additives can be included, suchas antioxidants or additional lubricity agents. The base lubricantcomprises from about 50-90%, preferably 65-90%, by weight polybutene,from about 230%, preferably 3-10%, by weight solid lubricant, from about05-10%, preferably 2-10% by weight lead or tin soap and from about05-10%, preferably 2-8%, by weight of a dispersing agent. The baselubricant can be applied directly to the die or workpiece surfaces, butpreferably the lubricant is diluted with a light hydrocarbon liquid witha low flash point, such as kerosene, diesel oil or stove oil. Dilutionscan be up to one part base lubricant to ten 3,806,453 Patented Apr. 23,1974 parts diluent (by weight), but, preferably, the dilutions rangefrom about 1:05 to 1:5 (by weight).

Except for the solid lubricant, the various components of the baselubricant must be soluble in the polybutene. In preparing the lubricant,the soluble components are first dissolved in the polybutene. Thematerial may be heated slightly, e.g., up to 170 F., to facilitate themixing and dissolving of the various components in the polybutene. Thesolid lubricant usually is not added until just before the lubricant isto be used because the solid lubri cant has a tendency to settle out.Conventional methods of applying the lubricant can be used, such asspraying or swabbing.

The lubricant of the present invention when applied to the hot surfacesof the workpiece or die readily wets and spreads on the hot metalsurfaces even if residual lubricant is on the surfaces from prioroperations. During forging operation, there is little or substantiallyno visible emissions or hydrocarbon emissions because the lubricant ofthe present invention flashes quickly and burns cleanly. Moreover, dueto the excellent lubricating properties of the present invention,significantly less lubricant need be applied for metal workingoperations. No significant buildup in the die is noticeable because thelubricant tends to remove and disperse within the lubricant any residueleft on the die surfaces.

The function of the dispersing agent is to insure that the solidlubricant remains uniformly dispersed throughout the lubricant as thelubricant spreads and dries on the hot surface. This function is readilydetermined by placing a drop of the lubricant containing graphite as thesolid lubricant on a hot metal surface (i.e., 500 F.). The color of thedried residue will be uniformly black if the function is properlyperformed. If the graphite is not properly dispersed, the color of theresidue on the surface will not be uniformly black, and will have amulticolored ring around the edges of the dark residue. Suitable organicdispersing agents include polyamino alkenyl succinimide, calcium saltsof an alkyl or alkene substituted salicyclic or succinic acid whereinthe substituted portion has from 10-30 carbon atoms, and calcium andbarium salts of naphthenic acids and long chain aliphatic sulfonic acidshaving from 10-30 carbon atoms.

The polybutene preferably has a viscosity from about to 100,000 SSU at100 F. (an average molecular weight of about 300 to 1200). Generally,the higher the metal working temperatures, the higher the viscosity ofthe polybutene should be. In the hot forging of light metal products,such as aluminum, wherein the die temperature is about 500-650 F. andthe workpiece temperature is from about 700-900 F., a polybutene havinga viscosity from about 500-5000 SSU at 100 F. has been found adequate.With higher metal working temperatures, correspondingly higher viscositypolybutene should be used. Particularly suitable polybutenes includePolybutene Nos. 8 through 16 manufactured by the Chevron ChemicalCompany. Typical properties of suitable polybutenes are given in thetable below.

Typical properties of polybutene Specific gravity 0.85-0.91 Viscosity at100 F., SSU 100-100,000

Flash point F.) 250-480 Fire point F.) 290-560 Bromine number, g./100 g.15-45 Neut. number, mg. KOH/g. 0.01 Carbon residue, percent None Thesolid lubricant is preferably graphite, although other solid lubricants,such as molybdenum disulfide and boron nitride can be employed with thepresent invention. The solid lubricant can be in powder or flake formbut should have a particle size less than 200 mesh.

The lead and tin soaps of the present invention, which function aslubricity agents, preferably are the lead and tin salts of saturated orunsaturated fatty acids having from -30 carbon atoms and the lead andtin salts of naphthenic acids. The most useful soaps are leadnaphthenate and stannous oleate. Other metallic soaps, such as aluminum,zinc and magnesium soap, were found detrimental to the forgingoperation.

In addition to the lead or tin soaps, other lubricity agents can beadded, such as synthetic sperm oil and epoxidized soybean oil. Examplesof the latter two are respectively P & G Continuous Casting Lubricant #6manufactured by the Proctor and Gamble Corporation and Paraplex G-62manufactured by the Rohm & Haas Company. Other lubricants includelanolin, fatty acids, fatty alcohols, fatty acid esters and the like.These additive lubricity agents must not, however, interfere with thespreading characteristics of the base lubricant, they should bethermally stable, and they should not significantly interfere with theability of the base lubricant to remove and disperse within thelubricant any residue left on the die surface. Other additives, such asantioxidants, can also be used. As mentioned previously, the variouscomponents must be soluble in the polybutene.

The following examples are given to illustrate the lubricant of thepresent invention:

The above lubricants were diluted 1:1 (by weight) with kerosene andemployed in the hot forging of aluminum automotive wheel hubs. Dietemperature was about 650 F. and workpiece lay on temperature was about800 F. The lubricant was sprayed onto the die surfaces for both blockingand finishing operations. Little or no build-up of residue wasnoticeable on the dies and no problems were found with the workpiecesticking to the dies. The lubricant was found to flash quickly and burncleanly, resulting in little or no smoke and essentially no hydrocarbonemissions. In the finishing operations, which required two forgingstrokes, it was found that only one application of lubricant was needed.As a comparison, when using conventional lubricants in the aforesaidforging operation, the application of lubricant was necessary for eachfinishing stroke.

In the above examples, the dispersing agent was OLOA 1200 manufacturedby the Chevron Chemical Company. The synthetic sperm oil was P & GContinuous Casting Lubricant #6 manufactured by the Proctor and GambleCompany. The antioxidant was Ethyl Antioxidant #702 manufactured by theEthyl Corporation. The polybutene was Polybutene 12 manufactured by theChevron Chemical Company. The epoxidized soybean oil was Paraplex G-62manufactured by the Rohm & Haas Company. The graphite was an airspungraphite, #200-10 manufactured by The Joseph Dixon Crucible Co. (averageparticle size 2.5 microns, specific surface 11.5 m. /gb.).

Although the above invention has been more specifically described interms of hot working and, in particular, hot

forging of light metal products, such as aluminum, the base lubricantcan also be used in cold forging operations, in which case, it may bedesirable to use water as the diluent material. If water is used, theaddition of an emulsifier may be required so as to emulsify the oil baseconstituents in the water. Suitable emulsifiers include water-misciblesoaps, such as triethanolamineoleate, sodium soaps of tallow and/ or oneor more of the commonly used nonionic emulsifiers useful for makingoil-in-water emulsions. Moreover, the lubricant can be used in othermetal working operations where relatively viscous, solid lubricantcontaining lubricants are employed, such as in tube and rod drawing.

It is obvious that various improvements and modifications can be made tothe present invention without departing from the spirit of the inventionor the scope of the appended claims.

What is claimed is:

1. A metal working lubricant comprising from about 50-90% by weightpolybutene having a molecular weight from about 300 to about 1200, fromabout 2-30% by weight solid lubricant selected from the group consistingof graphite, molybdenum disulfide and boron nitride, from about 05-10%by weight of a metallic soap selected from the group consisting of leadsoaps and tin soaps and from about 05-10% of an organic dispersingagent.

2. The lubricant of claim 1 wherein said polybutene has a viscosity fromabout IOU-100,000 SSU at F.

3. The lubricant of claim 1 wherein said polybutene has a viscosity fromabout 500-5000 SSU at 100 F.

4. The lubricant of claim 1 wherein said solid lubricant is graphitehaving a particle size less than 200 mesh.

5. The lubricant of claim 1 wherein said lead soap is selected from thegroup consisting of lead salts of fatty acids having from 10-30 carbonatoms and lead salts of naphthenic acids.

6. The lubricant of claim 1 wherein said tin soap is selected from thegroup consisting of tin salts of fatty acids having from 1-0-30 carbonatoms and tin salts of naphthenic acid.

7. The lubricant of claim 1 wherein said soap is selected from the groupconsisting of lead naphthenate and stannous oleate.

8. The lubricant of claim 1 containing a minor amount of a lubricityagent selected from the group consisting of synthetic sperm oil andepoxidized soybean oil.

9. The lubricant of claim 1 diluted with a diluent selected from thegroup consisting of kerosene, stove oil and diesel oil in amounts up to1 part lubricant to 10 parts diluent by weight.

10. The lubricant of claim 1 comprising from about 65-90% by weightpolybutene, from about 3-10% by weight solid lubricant, from about 2-10%by weight metallic soap and from about 2-8% by weight dispersing agent.

11. The lubricant of claim 1 wherein the lubricant is diluted with saiddiluent in amounts from about 1:05 to 1:5 by weight.

12. The lubricant of claim 1 wherein said dispersing agent is selectedfrom the group consisting of a polyamino alkenyl succinimide, calciumsalts of an alkyl or alkene substituted salicylic acid wherein saidalkyl or alkene group has from 10-30 carbon atoms, calcium salts of analkyl or alkene substituted succinic acid, calcium salts of naphthenicacid, calcium salts of long chain sulfonic acids having from 10-30carbon atoms, barium salts of naphthenic acids and barium salts of longchain sulfonic acids having from 10-30 carbon atoms.

13. The lubricant of claim 1 containing an emulsifier selected from thegroup consisting of water miscible soaps and nonionic emulsifiers andemulsified in water.

14. In the method of forging metal products wherein a workpiece isplaced on a die surface and pressure is applied to said workpiece so asto deform same into the die cavity, the improvement comprising applyingto the surfaces of said workpiece or said die a lubricant comprisingfrom about 50-90% by weight polybutene having a molecular weight from300 to about 1200, from about 230% by weight solid lubricant selectedfrom the group consisting of graphite, molybdenum disulfide and boronnitride, from about 05-10% by weight of a metallic soap selected fromthe group consisting of lead soaps and tin soaps and from about 05-10%of an organic dispersing agent.

15. The method of claim 14 wherein said lubricant is diluted with adiluent selected from the group consisting of kerosene, stove oil anddiesel oil in amounts up to 1 part lubricant to 10 parts diluent byweight.

16. The method of claim 15 wherein the lubricant is diluted with saiddiluent in amounts from about 1:0.5 to 1:5 by weight.

17. The method of claim 14 wherein said metal is aluminum.

References Cited UNITED STATES PATENTS DANIEL E. WYMAN, Primary ExaminerI. VAUGHN, Assistant Examiner US. Cl. X.R.

